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2010 2.5X Premium
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Discussion Starter #1
Does anyone over inflate their tires a bit to improve mpg? I'm curious as to the handling affects of increasing by 5psi so 37 front / 35 rear at 60F. What kind of pressure are you guys running and what is the consensus on max safe psi before the tire bulges on wears in the center more and handling/safety comes into question. thanks.
 

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2007 Forester Sports XT 4EAT
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The right tire pressure will depend on your tires & how you drive. We set our tire pressure for optimal performance, more than optimal mileage. To tell you the truth, I never check my mileage... stopped worring about it when I went for a turbo! We have Toyo Proxes 4 tires on all our vehicles & after trying different tire pressure combinations, we found 36F/34R was the "sweet" spot for this tire. :wink:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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Each brand of tire has its max PSI rating on it. Ive had different brands go from 50 to as low as 35psi max. I currently run mine at 5psi over stock to get better mpg possibly. They say it may adversely affect handling since rolling on a smaller contact patch is the result of over inflating.
 

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2009 Forester 2.5x
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702 Posts
I do run my tires a few lbs. over what the OM manual suggests, no adverse effects ever noted. I think most manufacturers build in a "cushy" factor to the air pressure reco, as in : those darn Americans want a nice cushy ride, how low can we set the pressure and still be good?"
just my .02
Steve
09 2.5X AT (36F 34R)
 

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2004 Forester 2.5X 5 speed manual
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2,136 Posts
I'm curious as to the handling affects of increasing by 5psi so 37 front / 35 rear at 60F.
These are the same pressures I currently run my tires at, but I don't know about temp. I just check the tires first thing in the morning while it's still cool and the vehicle is in the shade.

The current set of tires I have on my Forester are 2 ply sidewall. Running them at the factory recommended pressure was way too soft. At 37 front / 35 rear they feel approximately the same as the previous set of single ply tires at 31 front / 29 rear.
 

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2003 Subaru Forester XS
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167 Posts
I have the Michelin Pilot Exalco, they have max. inflation of 44psi, but once i go over 36psi cold they slip like crazy, so i keep them on 32psi front and 34psi rear - it kills the understeer a bit that way:biggrin: Personally, i think it really depends on the tires and the compromise with the handling .
 

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2005 Impreza RS Wagon Auto
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I wouldn't recommend 40+psi, the more you increase the pressure over the oem specs the less traction you will get (dangerous) and you wear your tires oddly. I personally like 34f/32r sometimes 36/34.
 

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my experience was drastic.

when i purchased my2010 forester from the dealer, all tires were set high.. 38psi. i ran like that for one weekend and changed after reading the manual's recommendations.

so i dropped all tires to 32psi all around. i dont agree with the mismatch pressures - i think that will wear the tires differently, personally i dont want that.

3 days later i noticed my MPG drop so fast. the gas gauge used to stay at full for at least 100km and only after 60km was already dropping fast! so this was a 40km difference per quarter tank! :icon_eek:

i quickly refilled my gas and refilled the tire pressure, this time i went up to 39psi all around.

my MPG is back up where it should be. around 600km+ / tank.

the ride is rougher but hey my MPG is great.:icon_biggrin:
 

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2007 Forester Sports XT 4EAT
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^^ I use a higher tire pressure in the front to carry the extra weight & a bit less in the rear where there less weight. In addition, I try different pressure setting to see how the tires sit & how my Forester handles. I have to admit I'm more into performance, than mileage gains. :wink:

You can run higher air pressure for mileage gains, but that can also overstress your suspension. Make sure you keep an eye on how your tires are wearing. I noticed when I ran a higher tire pressure, I had way more bounce steering on rough roads & the tires would want to follow ruts in the pavement. :frown:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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2019 Crosstrek 2018 XT
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I keep 35 to 36 all around. Once you go above that the thing seems to drift and seems more "squiggly" if that's a word. If you have a very heavy load on it a bit more is probably fine.
 

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2015 Highlander AWD XLE 6AT
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I'm presently using 34 F & 32 rear, which is 2 psi above the factory spec for my '09 car's 225/55R17 tires. I might try 35F & 34 rear.

Incremental changes (i.e., +2 psi, or +3 psi) should perhaps be referenced against the factory specs, which vary by MY, tire size, and load. For examples, see the attached chart.

HTH,
Jim / crewzer
 

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The Sub kit guy
2005 Forester X & XT VF39
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I have RE92s on my 05 X, and Subaru recommends around 34psi. A friend of mine with a Honda Insight has the same tires but Honda recommends running them around 45psi to help with mileage.
 
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